Field
Exemplary embodiments of the present invention relate to a light emitting apparatus, a planar surface light source apparatus, and luminous flux control for a deterministic light deviating member, such as a Total Internal Reflection (TIR) optical lens, and an absorption filter that improves the overall uniformity of a liquid crystal display (LCD) to 90% or more.
Discussion of the Background
In the past decade, flat-screen televisions have gone from mere luxury-status to a market domination status that is so complete that the market for cathode-ray tube (CRT) televisions has been greatly reduced in size. While plasma flat-screens are similar to CRTs in having emissive pixels, the pixels of LCDs are passive, merely acting to rotate the polarization of light passing through them, so that they must be put between two orthogonal polarizers in order for the pixels to act as intensity modulators.
Originally, flat-screen LCDs provided this intensity by utilizing waveguide-based backlights that were edge-illuminated by fluorescent tubes. As light-emitting diodes (LEDs) have increased in brightness and efficacy, they replaced the fluorescent tubes while retaining the edge-illuminated waveguide. However, waveguides may be thick and heavy for large screen sizes, so that direct-view area backlights comprising hollow light boxes may be desirable because their lights are distributed all across the back of the light box. Direct-view area backlights may spread the light out uniformly to eliminate hot spots on the screen just over each LED light source, which is what LEDs without dedicated local lenses may not accomplish.
As LED technology has matured, increasing power output means that fewer LEDs may be needed to do any particular illumination task. When area backlights use fewer LEDs, especially considering the 16:9 proportions of typical high-definition televisions, uniform illumination geometry may become increasingly difficult to achieve.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.